Description: The vestibulo-ocular reflex (VOR) is a set of reflexes activated by two forms of head acceleration; angular (the AVOR) driven by the semicircular canals, an linear (the LVOR) driven by the otoliths. Because linear accelerations arise during both translational motion and head tilt relative to gravity, but requir different compensatory responses, the LVOR is comprised of translational and tilt forms. During the previous period of support, the response dynamics of th LVOR, its modulation by fixation distance, and its interactions with vision an the AVOR were studied. The studies in this proposal are the logical sequel of the work done during the last period. Several new questions will be addressed. 1. Are the different LVORs driven by distinct sets of labyrinthine inputs and processed by independent central pathways? 2. How are linear accelerations properly parsed into tilt and translation, given that the otoliths respond ambiguously to them? 3. Are the various LVOR and AVOR components and parameter under independent adaptive control, or do they share elements? 4. Finally, since the VOR and motion perception share common sensory inputs as well as goals of spatial orientation, do these perceptual processes have similar properties and limitations? New experiments are described that will address these concerns in both humans and monkeys. Novel techniques will be explored, and specific endorgan lesions will be employed to directly assess the origin o VOR behaviors and elucidate processes that restore function.